The construction industry is one of the most environmentally detrimental industries in the world, impacting directly the use of raw materials, their determination of use involving the whole lifecycle, as well as all their surrounding environment. However, within the building sector, the transition from a linear to a circular economy is still at an early stage. Business models need to be reconsidered to include new and improved methods and innovative services that could lead to a net reduction in the use of resources and minimizing the waste disposed on landfills. In this context, an important role in buildings’ circularity is “deconstruction”, which is understood as a well-considered selective dismantlement of building components, in prevision of a future reuse, repurposing, or recycling. It represents a sustainable alternative to common demolition, which tends to be an arbitrary and destructive process, and although faster and cheaper, it typically creates a substantial amount of waste. The purpose of this article is to analyze the deconstruction potential of buildings and the strategies to apply in order to keep the impacts on the urban environment low. The article aims to facilitate the implementation of circular economy strategies for buildings by proposing common principles for deconstruction as a sustainable alternative to demolition and defining the key points to be applied during the design and planning process regardless of the type of construction system or material used.

Water in the city is typically exploited in a linear process, in which most of it is polluted, treated, and discharged; during this process, valuable nutrients are lost in the treatment process instead of being cycled back and used in urban agriculture or green space. The purpose of this paper is to advance a new paradigm to close water cycles in cities via the implementation of nature-based solutions units (NBS_u), with a particular focus on building greening elements, such as green roofs (GRs) and vertical greening systems (VGS). The hypothesis is that such “circular systems” can provide substantial ecosystem services and minimize environmental degradation. Our method is twofold: we first examine these systems from a life-cycle point of view, assessing not only the inputs of conventional and alternative materials, but the ongoing input of water that is required for irrigation. Secondly, the evapotranspiration performance of VGS in Copenhagen, Berlin, Lisbon, Rome, Istanbul, and Tel Aviv, cities with different climatic, architectural, and sociocultural contexts have been simulated using a verticalized ET0 approach, assessing rainwater runoff and greywater as irrigation resources. The water cycling performance of VGS in the mentioned cities would be sufficient at recycling 44% (Lisbon) to 100% (Berlin, Istanbul) of all accruing rainwater roof–runoff, if water shortages in dry months are bridged by greywater. Then, 27–53% of the greywater accruing in a building could be managed on its greened surface. In conclusion, we address the gaps in the current knowledge and policies identified in the different stages of analyses, such as the lack of comprehensive life cycle assessment studies that quantify the complete “water footprint” of building greening systems.

Urban strategies and the way cities are planned have changed throughout history, adapting to the needs of the inhabitants, infrastructure requirements, and advances in technology. Uses and customs of people and cities are changing and can evolve much faster than in the past, with the result that urban planning is often too slow to adequately meet the current needs of society. In this context, the development of pop-up environments for temporary developments could be a solution to meet the needs of flexibility, adaptation, and resilience of a city. This allows the urban planner to consider systems from a short-term perspective, fulfilling current needs without compromising the development of potentially different activities in the future. The purpose of this research work is to outline the general requirements of pop-up environments in urban developments that allow for adequate integration into urban planning strategies. Based on an extensive evaluation of the existing literature and a series of case studies, the paper analyzes the key elements that define the framework conditions of urban planning strategies for temporary developments that generate a positive impact on the overall urban system.

The development and application of appropriate Circular Economy indicators is an issue that concerns both the scientific and the business community, as well as decision makers. The existing gap between research, policy and practice could be bridged by using a dynamic indicators selection approach that combines both expert and participatory practices. This study aims to develop such a novel approach for the selection of indicators based on views and needs of practitioners, whilst considering the complex interdependencies of the indicators and determining their importance. Twenty circularity indicators for the Water-Energy-Food-Ecosystems nexus are selected and ranked by different stakeholders. The interrelationships of the indicators are identified using the Interpretive Structural Model, resulting in six levels of importance. Cross-impact matrix multiplication applied to classification (MICMAC) analysis further enabled the classification of the twenty indicators into four categories based on their driving and dependence power. The results indicate that seven indicators—one related to regeneration of natural environment principle, four related to keep resources in use, and two related to design out negative externalities—are the driving indicators to Circular Economy. The approach can be applied to other sets of indicators as well, enabling their prioritization and implementation with other systems.

The housing sector is responsible for more than 50% of global resource extraction, about 50% of world energy consumption, 1/3 of water consumption and furthermore generates about 1/3 of all produced waste. A new, circular approach is needed to enable better decision-making on the selection of innovative architectural solutions for all phases of a building's life cycle. The current building sector's business model must be redesigned to include the application of new and improved methods, solutions and innovative services, and advance a positive transition from a linear economy to a circular economy. We will present the circular interventions carried out on a centenary building located in Vienna in the framework of the HOUSEFUL project. HOUSEFUL is an EU-funded initiative with the objective to develop and demonstrate integrated circular services, focusing on the optimal management of resources throughout the life cycle of new or existing buildings. The demonstration will include technologies to circulate all process flows while reducing the overall energy demand. These technologies will be offered as integrated services to produce treated rain and wastewater for internal reuse, the generation of renewable energy from biogas, compost production combined with urban gardening and for the use of nutrients in a greenhouse. The design of more efficient processes, such as green walls, innovative conservatories, building-integrated solar thermal and photovoltaic panels will improve building energy efficiency. All process flows will be intensely monitored to ensure safety and collect data for further replication cases. The solutions will also include the use of sustainable and upcycled materials and the implementation will be based on the principles of reversibility and de-constructability. The final services of the building will be elaborated in co-creation workshops with a multitude of stakeholders. Additional service-oriented modelling facilitates replication for the transition to the circular housing sector.